Natural killer cells

Natural killer cells (also known as NK cells, K cells, and killer cells) are a type of lymphocyte (a white blood cell) and a component of innate immune system. NK cells play a major role in the host-rejection of both tumors and virally infected cells.

Function

NK cells are unique as they have the ability to recognize stressed cells in the absence of antibodies and MHC, allowing for a much faster immune reaction. They were named "natural killers" because of the initial notion that they do not require activation to kill cells that are missing "self" markers of MHC class I.

Development

NK cells are derived from hematopoietic stem cells (HSCs) in the bone marrow. They then travel to the thymus, where they undergo a process of maturation and differentiation.

Activation

NK cells are activated in response to interferons or macrophage-derived cytokines. They serve to contain viral infections while the adaptive immune response is generating antigen-specific cytotoxic T cells that can clear the infection.

Clinical significance

NK cells are being used in immunotherapy to treat patients with cancer. They have shown promise in the treatment of leukemia, lymphoma, melanoma, and breast cancer.

See also

• Adaptive immune system
• Innate immune system
• Lymphocyte
• White blood cell

References

Natural killer cells Resources
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